Question: Subtract. $\dfrac{4}{5} - \dfrac{9}{12} = $
Explanation: Before we can subtract our fractions, they need to have the same denominator. $\frac{1}{5}$ $\frac{1}{5}$ $\frac{1}{5}$ $\frac{1}{5}$ $\frac{1}{5}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\frac{1}{12}$ $\dfrac{4}{5}$ $\dfrac{9}{12}$ $\dfrac{4}{5}-\dfrac{9}{12}$ Let's look at the multiples of each denominator and see which multiples they have in common. Denominator Multiples ${5}$ $5, {10}, 15, 20, 25, 30, 35, 40, 45, 50, 55, \underline{60}$ $12}$ $ 12, 24, 36, 48, \underline{60}$ The least common denominator is ${60}$. Let's use multiplication to make each fraction have a denominator of $60$. ${\dfrac{4}{5}}=\dfrac{{4} \times {12}}{{5} \times {12}} = {\dfrac{48}{60}}$ $\dfrac{9}{12}}=\dfrac{9} \times 5}{12} \times 5} = {\dfrac45}60}}$ Now, we can subtract ${\dfrac{48}{60}} - \dfrac{45}{60}}$. $\dfrac{48}{60}$ $\dfrac{45}{60}$ $\dfrac{48}{60} - \dfrac{45}{60}$ $=\dfrac{{48}-45}}{60}$ $= \dfrac{3}{60}$ ${\dfrac{4}{5}} - \dfrac{9}{12}} = \dfrac{3}{60}$ We can also write $\dfrac{3}{60}$ as $\dfrac{1}{20}$.